Semiconductor modules are used for vehicular motor control and the like, and there is a continuing demand for size and weight reduction of such modules. In order to realize size reduction, a structure for efficiently cooling semiconductor devices is indispensable. Therefore, development of a direct cooling structure, in which semiconductor devices are directly joined onto cooling fins and directly cooled, has been advanced.
A semiconductor module in which semiconductor devices are directly cooled with fins has been suggested (see, for example, PTL 1). However, since there are a total of three connection ports, namely, two inflow ports and one outflow port, the mounting process can be complicated. Further, cooling of the fins advances in a path connecting the inflow port and the outflow port, but it is difficult for cooling water to flow to the outside of the path, and the cooling performance is lowered. As a result, more uniform cooling performance cannot be obtained.
A cooler-integrated semiconductor module has also been suggested (see, for example, PTL 2). However, since cooling water collides, without being divided, with fins, a long flow path in one direction is realized, and a large difference occurs in the cooling performance between a device on the upstream side and a device on the downstream side.
In addition, a cooler-integrated module in which cooling water is divided has also been suggested (see, for example, PTL 3). However, the jets of cooling water collide directly against the fins, dynamic pressure is generated, and the fins are subjected to large stress. For this reason, high strength is required for the fins. Increase in pressure loss due to dynamic pressure generation is also a concern. Furthermore, since water flow is greatly disturbed in the flow path when water is jetted from a plurality of jet openings, the process is difficult to control and eventually a large difference in cooling performance occurs between the inflow side and the outflow side.